[David Van Wickler]

Welcome to the Phorum!!!!  

As Mike and Terry said, that cap that was tacked in under the chassis was probably an old repair to replace the original electrolytic cap that had died. The old cap is probably an aluminum can that sits above the chassis with the lug below.  You can take off the replacement cap and stuff new electrolytic cap into the can.  There are a number of threads showing how to do that but here's one to start that gives you and idea of what to do.  You will need to replace all electrolytic and paper caps.  mica caps are likely still good.  Also check and replace resistors that have drifted high (>20%).  Some folks replace all resistors any way.  1940 sets may have rubber coated wires that need replacing as well.  See this thread.

Thanks - yes I'm a newbie/am, but can use a multimeter and can solder. The original cal looks like it's insulated from the chassis. so is there a ground somewhere? 

Also I believe the repair was made because the clamp screw is facing the radio chassis and you'd have to remove the entire frame assembly to access the screw.

My 2nd question is what is the best way to check the resistors? there seems to be close to 800 of them. 

And so when I replace all the caps and drifted resistors when can I plug it in to see if it works? I don't want to let any smoke out. Does  anyone have an amateurs checklist of what can be done with a multimeter and soldering iron and capable of reading a schematic , but doesn't have any of the fancy tech gear?

I get the feeling that without oscilloscopes, tube testing dodads and a doctorates in schematic reading is it easier to send it to a shop and have a professional do this?